1. Field of the Invention
This invention relates to a vehicle battery charging system and, more specifically, to such a battery charging system that can be installed on one vehicle for selectively charging the battery of the one vehicle from another vehicle or visa-versa.
2. Description of the Prior Art
It is not uncommon for the battery of a vehicle to be inadvertently discharged to the extent the there is insufficient power to be able to crank and/or start the vehicle. Such a condition may arise because the operator of the vehicle has mistakenly left the lights, radio, or other electrical power consuming device or accessory running in the vehicle after the ignition has been turned off. Without the engine, and thus the alternator, running, the only source of power is the battery which in time can be sufficiently depleted to reduce its reserve capacity below that needed to restart the engine. A similar reduced capacity condition for the battery can occur when the battery has degraded with age so that it is incapable of starting the vehicle at a low ambient temperature or is near the end of its useful life and is incapable of holding a charge over a long period of time.
It is recognized by those skilled in the art that a vehicle battery under such conditions is often referred to as a "dead" battery even though it is only depleted to an extent that it is incapable of starting the engine. There must be sufficient power capacity in the battery that can be sustained for a long enough time for the starter relay to be closed and remained closed to be able to deliver an appropriate starting current to the starter motor to initiate the starting operation of an internal combustion engine. If the internal combustion engine is a standard engine, sufficient power must be maintained at the spark plugs to sustained ignition. If, on the other hand, the engine is a diesel engine, there must be sufficient power to maintain glow plug activation for the starting sequence of the diesel engine. There are several recognized means for restoring a battery to a charged condition. The most common includes starting the engine, by whatever means is available, and allowing the alternator of the running engine to simply recharge the battery through a normal recharging circuitry typically incorporated in the electrical system of most vehicles. Alternatively, an outside source can be connected to the dead battery to raise its capacity sufficiently to enable it to then provide its normal function of supplying the power needed to start the engine.
U.S. Pat. No. 5,194,799 discloses a booster battery assembly that serves as a power source, in addition to the normal vehicle battery, that can be used to start the engine of the vehicle if the normal battery is incapable of providing starting power. Once the engine of the vehicle is started with the booster battery, the alternator will allow the continued operation of the vehicle, the recharging of the normal battery, and, perhaps, the recharging of the booster battery, so that the vehicle can be started by either the normal or booster battery when needed the next time. This system is unusual and not normally preferred because of the need to provide a permanent additional battery.
Instead, the normal means used to start an engine having a depleted battery includes some type of "jumper" system which allows the temporary connection of a secondary power source to the vehicle electrical circuitry for starting of the engine. Once the engine is running, it is capable of continued operation though the use of the alternator without any further need for the secondary power source.
U.S. Pat. Nos. 3,590,357; 4,157,492; 4,757,250; 4,769,586; and 4,885,524 disclose systems that can be temporarily connected to the electrical circuitry of a vehicle to provide some type of "jumping" power for starting the engine of the vehicle. Once the engine is started, the system can be disconnected so that the normal battery can be recharge by the engine. While all of these systems include a number of specific elements and features intended to increase their reliability or effectiveness, they basically function in a manner that is well known to most vehicle operators who have previously used less sophisticated "jumper cables" systems.
Serious dangers can exist by the improper use of these less sophisticated jumper cables that simply employ a pair of cables with alligator-type clamps for respectively connecting the positive terminal of the active battery to the positive terminal of the weak battery and the negative terminal of the active battery to the negative terminal of the weak battery. A first danger can exist by the incorrect connection of the positive terminals to the negative terminals. A second danger could result in a battery gas explosion that could occur by the production of sparks at a terminal that could ignite hydrogen gas given off by the battery.
If the polarities of the batteries are mismatched or reversed, that is, with the positive terminal of each battery connected to the negative terminal of the other battery, serious damage can occur to the batteries, the booster cables, and even to the electrical system of the vehicles. Furthermore, and more importantly, the electrical connection of two batteries in the state of reverse polarity can cause an explosion that would place the individual performing the "jumping" procedure at great risk of personal injury.
Batteries, of the type found in automobiles, boats and other vehicles, generate hydrogen and oxygen gases at the plates thereof that are highly explosive. In the event that these gases escape and collect in the vicinity of the terminals of the battery, they can be ignited by any sparks or arcing at the terminal. Such a combustion could rupture the battery casing and cause electrolyte (sulfuric acid and water) to be sprayed or spilled over an individual or object in the immediate vicinity.
U.S. Pat. No. 3,590,357 discloses a complicated system including two twelve volt batteries that may be employed to provide a "boost" to another twelve volt battery or a twenty-four volt battery of another vehicle that has insufficient power to start the vehicle. Although the system includes a polarity detector system, some minimum voltage on the weak battery is required to operate the polarity detector. Although the overall system is quite complicated and expensive, it includes nothing to prevent a possible electrical flash or explosion that would be possible by the introduction of sparks at the weak battery.
U.S. Pat. No. 4,157,492 discloses a specifically designed jumper cable system that includes mechanical means for insuring that the polarity is correct. Unfortunately, both cars would be required to employ compatible hardware including costly "high current" equipment. There is no evidence that such a system has been accepted for the reliable jumping of one battery by another.
U.S. Pat. No. 4,757,250 discloses a three cable booster assembly that is intended to prevent the production of sparks that could result in a battery explosion. The cables include a polarity indicator to indicate if the cable is not properly connected so that the operator will be able to reposition the cables until the correct polarity is obtained. Assuming that the polarity is correct, a time delay circuitry prevents the actual connection between the batteries until there is contact made at each of the terminals. This is intended to minimize the possibility of any sparking that could occur through temporary contact made at the terminals themselves during the connecting process. There is means provided to prevent any current flow between the terminals if there is an interruption of contact at one of the positive terminals. This is intended to prevent a spark from being created if contact is inadvertently interrupted at a particular positive terminal. The components required to provide these safety features appear to be very complicated and expensive and require high current cables to support the current needed to start the engine.
U.S. Pat. No. 4,769,586 discloses battery jumper cable apparatus that includes complicated circuitry for allowing the ends of the cables to be connected to either battery terminal of the batteries by incorporating internal sensing and coupling means to selectively connect the batteries with proper polarity. This "automatic" coupling is relatively complicated and requires expensive components to insure the positive terminals are connected and the negative terminals are connected during the booster operation.
U.S. Pat. No. 4,885,524 includes an entire vehicle battery system that employs an adapter over the battery thereof to provide polarized connections to the starter system of the vehicle and for a cable that includes a remote polarized coupling at the grill of the vehicle. If this system were to be universally accepted, polarized connection could be made at the grills of two similarly configured vehicles for jump starting the battery of either vehicle from the other. However, one embodiment recognizes the likelihood that another vehicle may not have a similar system and, therefore, utilizes a jumper cable having the polarized adapter to the grill of the one vehicle with connector clamps for the battery of the other vehicle that is not so configured. When utilizing such a configuration, it is clear that the temporary connection being made to the second vehicle that does not employ the polarized system must be carefully done to insure that the polarity is proper to prevent the problems associated with reverse polarity as discussed above.
The systems which include jumper cables are intended to provide a high current boost from a charged battery of one vehicle to the ignition system of a second vehicle having a weak battery so that the engine of the second vehicle can eventually be employed to charge the weak battery. However, there are different systems which allow the independent direct "trickle" charging of a weak battery itself. A number of well-known battery charging systems, such as that disclosed in U.S. Pat. No. 4,829,223, convert normal alternating current to direct current to slowly and directly charge a weak battery without the use of the battery system of another vehicle. Other systems like those disclosed in U.S. Pat. Nos. 4,829,223; 3,806,790; 4,258,305; and 4,617,506 are intended to provide a relatively low direct current for charging of a weak battery from a fully charged battery of another vehicle over an extended period of time.
U.S. Pat. No. 4,829,223 discloses a typical battery charging system that employs alternating current, for example, from a house wiring system. The battery charger converts the alternating current to direct current to provide a trickle charge to a depleted battery of a vehicle. In order to insure correct polarity with the battery being charged, the overall system employs cable means connected to the battery terminals to provide a polarized female plug that can be connected properly to the male plug from the battery charger. There is no specific indication of the amount of time that would be required to recharge the depleted battery. However, unless such a battery charger is a heavy-duty type that might be utilized at service stations, it is expected that the charging time would be greater than an hour and could be several hours.
U.S. Pat. No. 3,806,790 discloses means for providing a dual battery charging system that automatically charges an auxiliary battery when the motor is operating and automatically disconnects the auxiliary system from the main system when the engine stops. While the system disclosed therein includes features that protect the auxiliary battery and insure that no damage would be done to the batteries if they are connected in a reverse, incorrect manner, the overall system is expensive and unlikely to be fully accepted because the requirement of a second battery.
U.S. Pat. No. 4,258,305 discloses a trickle charging device that, in its simplest form, includes a pair of cigarette lighter plugs having their negative contacts directly coupled together and having their positive contacts coupled by means of a current limiting device such as an incandescent bulb. In use, one of the plugs is plugged into the cigarette lighter socket of a vehicle having a discharged battery and the other plug is plugged into the cigarette lighter socket of a vehicle having a fully charged battery. A low current will flow from the good battery and the good battery charging system to the weak battery through the incandescent light to trickle charge the weak battery. The incandescent bulb serves the dual function of limiting the charging current and acting as a charging rate indicator. A shorting sleeve is also disclosed for shorting the contacts of one of the plugs so that the incandescent bulb can be used as an emergency light. The system discusses the preferred operation of the engine of the charging battery so that the electric generation system constantly recharges of the battery. Additionally, there is an indication that the preferred maximum charging current would only be about eight amps that would clearly be within the capacity of the wiring associated with cigarette lighter socket. According to the disclosure therein, the anticipated period of time required for a completely discharged battery to become recharged sufficiently to start most cars would be approximately 15 or 20 minutes. However, it is felt that any claim of such a short period of time would be extremely difficult to support and that the expected, low charging rate would require one or more hours to adequately raise a fully discharged battery to a level required to start a car.
U.S. Pat. No. 4,617,506 includes a battery trickle charging system that again appears to employ means for connecting the batteries of two vehicles through the cigarette lighter systems for charging a depleted battery from a fully charged battery. The vehicle having the fully charged battery would be started to insure that the battery system thereof is maintained at capacity during the trickle charge. Although there is no indication therein of the particular current flow through the system, it is expected that the charging time for restoring a depleted battery to a charged condition would again be one or more hours, as was the case with the device of U.S. Pat. No. 4,258,305.